Method of producing a spliced pictorial

ABSTRACT

Method of producing a spliced pictorial on transparent plastic film for application to large internally illuminated signs involving the steps of sectionalizing the pictorial, appropriately four-color printing each sectional while leaving a different two-color border on each of adjacent sectionals, and overlap splicing adjacent borders in registry to provide an inconspicious splice.

United States Patent 51 3,661,664

Lundell [451 May 9, 1972 METHOD OF PRODUCING A SPLICED e nces Cited PICTORIAL UNITED STATES PATENTS [72] Invent mi? whte Bear Lake 2,624,967 1/1953 Phillippi 156/63 x 3,516,893 6/1970 Gerard ..l56/277 X [73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn. Primary Examiner-Benjamin R. Padgett Assistant E.\'aminer-Stephen J. Lechert, Jr. [22] mm 1969 Attorney-Kinney, Alexander, Sell, Steldt & DeLaHunt [21] Appl. No.: 798,376

[57] ABSTRACT [52] U.S. Cl ..156/63, 156/ l 59, 156/265, I Method of producing a spliced pictorial on transparent plastic 156/266, 156/277, 156/299 film for application to large internally illuminated signs involv- [51 Int. Cl. ..B44c 1/00 ing the s p f sectionfllizing h pictorial, pp pri ly f r- [58] Field of Search ..l56/63, 157, 159, 277, 304, color printing each sectional while leaving a different twocolor border on each of adjacent Sectionals, and overlap splicing adjacent borders in registry to provide an inconspicious splice.

1 Claims, 5 Drawing Figures 'IH =E1; T: T:://0 4\J j/ Q-J/7 5; n 1M T1: r l 8 2 7 i il m i/[5 /,2- i

l l Fair Patented May 9, 1972 3,661,664

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METHOD OF PRODUCING A SPLICED PICTORIAL The present invention relates to a method and materials for providing graphic indicia used in the construction of internally illuminated signs of large sizes, especially those signs which are used for outdoor advertising in conjunction with restaurants, drive-ins, service stations, etc.

One or both faces of such signs are frequently made of sheets of transparent thermoplastic plastic material such as polymethyl methacrylate. In order to provide the advertising matter, graphic intelligence or other pictorial representation on the face of the sign, the past practice has been to paint such pictorial representation thereon, sometimes by a very timeconsuming process known as posterizing, which may require application of 30 or more colors of paint, and which is done quite similarly to the painting by numbers" art work where the paints have numbers and areas on the canvas have numbers corresponding to the paint to be used. Another method has been to reproduce the pictorial directly onto the sign face by using the silk-screen printing process.

A more recent method has been to silk-screen print the pictorial onto a flexible sheet of clear plastic film that has an adhesive on the opposite side thereof, and then to apply and adhere the printed sheet to the sign face. The latter materials and method have several advantages, e.g., it is easier for the screen processor to handle a 5 mil plastic sheet on a paper backing rather than a inch thick acrylic plastic sheet; errors in printing were less costly because the base was less costly in the case of the film; and, because the sign faces normally are formed with a raised front face and downwardly curved edges or borders, after being silk-screen printed any positional printing error involved an uncompensated distortion of the picture when the base sheet was formed and caused a loss of the entire acrylic sheet, whereas the vinyl film was applied after forming and any position printing error merely called for replacing the film. However, as the size of the internally illuminated signs has increased the width dimension has exceeded the width of the adhesive-coated plastic films which are commercially available, i.e., about 48 inches wide, and in any event, a major difficulty and disadvantage of silk-screen printing pictorials of such large size either onto the plastic film or directly onto the sign face base sheet remained, namely, if the printing job was almost finished and an error was made, for all practical purposes the best solution was to discard that particular sheet of film and start over.

Because of the aforesaid advantages of using the adhesivecoated film, attempts were made to four-color print the pictorial on 2 sheets of the film and butt-splice the adjacent edges in proper registration. However, due to either some slight elastic memory in the film or due to dimensional changes in the plastic face of the sign from changes in ambient temperature, or both; such butt splices were not successful because the slightest separation of the abutting edges would allow the internal light to shine directly through, and spoil the appearance of the sign.

On the other hand, an overlap splice was also unsuitable, because the overlapped area would appear, even when viewed from some distance, as a relatively dark seam to the viewer, and any slight shifting of the films would tend to worsen the appearance.

Therefore it is an object of the present invention to provide a method for producing inconspicuous splices in a colored pictorial while using transparent film to produce the pictorial without seriously detracting from the attractiveness of the sign due to the visibility of the splice area, and to novel materials for producing the aforesaid inconspicuous splice.

In producing colored pictorials, it is the practice to reproduce a full color original subject by screening the three basic process colors (yellow, magenta red and cyan blue) and then black in halftone dots, one after another in the order just mentioned, and in close register in order to make the reproduction. Accordingly, the invention will be described herein in terms of four-color screen process printing although it is understood that the invention is also applicable to fourcolor halftone printing by other methods, such as planographic printing, or three-color screening or printing, etc.

The present invention provides a method for producing at least one spliced area of a large pictorial that is produced from a plurality of four-color printed flexible plastic films, the printing on said films being differently colored half-tone dots which are laid down in a selected order and registration to produce the desired picture, the method comprising the steps of sectionalizing the pictorial to be produced, appropriately fourcolor printing each sectional while leaving a different twocolor border respectively on each of adjacent Sectionals, and overlap splicing adjacent borders in registry so as to supply only the amount of four-color printing at the overlapped areas necessary to provide the desired four-color density, whereby an inconspicuous splice is provided.

The present invention is further illustrated in the accompanying drawings in which:

FIG. 1 is a schematic representation of a front view of the numeral 4 printed on sections of transparent film in four-color halftone and applied to the front face of an internally illuminated sign, with the overlapped spliced areas of the sections shown by broken and straight lines, and

FIG. 2 represents a greatly enlarged schematic view of the right hand corner portion of the middle left hand section of film in FIG. 1, and

FIG. 3 represents a greatly enlarged schematic view of a portion of the lower left hand section of film in FIG. 1 and FIG. 4 represents a greatly enlarged schematic view of a portion of the lower right hand section of film in FIG. 1, and

FIG. 5 is a schematic representation of the symbols used in FIGS. 2, 3 and 4 to represent the yellow, red, blue and black halftone dots used in four-color printing.

For purposes of illustration and explanation, it can be assumed that the front face of the internally illuminated sign 10 in FIG. 1 has a width of 10 feet and a height of 12 feet, the numeral 4 per se being at its greatest dimensions about 6 feet wide and 10 feet high, and that it is merely representative of a four-color printed pictorial, which more commonly would be a reproduction of a human face, an animal, landscape, trademark or the like.

In order to produce the printed overlapped sign film for a pictorial, one preferably first selects areas in the pictorial in which the splice area naturally tends to be inconspicuous and blend into the surrounding graphic matter, e.g., at the junction line of the handle and the mug of a glass beer stein, at the area separating the beer and the foam, and where there is a darker shadow on the side of the mug, rather than in a highlight area, whenever such selection is possible, thereby making the ultimate dot registration somewhat less critical.

In producing the numeral 4 for FIG. 1, the lower left hand sections of film is of a different height than the height of the lower right hand section, thereby avoiding a four-section overlap, although it is possible to make the latter type splice, though not preferred.

After deciding on the splice areas, the silk-screen processor then proceeds to silk screen print on the sections of film in the usual fashion, except that in the area where the splice will occur (assuming for purposes of illustration that this particular area requires dots in all four colors) he prints to the splice edge of the film with but two of the four colors, and omits two of the colors for a distance of about 6 to A inch, or even up to about of an inch, although the more overlap in the splice region the more difficult it seems to become to precisely register the halftone dots.

Referring specifically now to the drawings, the numeral 4 in FIG. 1 has been constructed by applying the printed plastic film sections 12, 13 and 14 in overlapped relationship, in the order just recited, to the left hand exterior face of the sign, and then, again in ascending order, applying sections 15, 16 and 17.

Referring now to FIG. 3, the processor has consecutively applied yellow, red, blue and black process inks to the main body 20 of the segment of the numeral 4 occurring on those sections, but has so made or masked his silk screen that in the approximately 541 inch splice border area 21 along the side and top of this section only the yellow and red ink dots have been applied.

In FIG. 2, the section has been printed in similar fashion, a yellow-red only printed border 22 being lefl on the right hand edge, and a blue-black only printed splice border being made on the bottom edge of this section, corresponding in size to the top border 21 of section 12. lt should be noted that the lower right hand corner of section 13 as defined by the edges of borders 22 and 23 has been removed from this section.

In FIG. 4 area has been fully printed, but a left hand splice border edge 24 of a width corresponding to the width of border 21 has been printed in blue-black only, and a top splice border 25 has been printed in yellow-red only.

Sections 14, 16 and 17 and the top portion of section 13 are printed in an analogous fashion with the appropriate two-color only border sections.

It will be seen that when the sections are applied to the front face of the sign in the order above mentioned and in registry the yellow ink is furthest from the viewer, and the black ink is closest. The notch that was cut in the lower right hand corner of section 13 avoids the application of too great an ink dot density to this area of the splice in a situation like the present one where three sections overlap in a particular area. Rather than cutting out such areas, they may merely remain free of ink, if desired.

In silk screening the sections it is preferred to avoid screen sizes smaller than openings per linear inch, to avoid problems in registration.

A presently preferred clear vinyl film for use as sign sections is a relatively dimensionally stable film having a coating of weather resistant alkyl acrylate pressure-sensitive adhesive of the type disclosed in U.S. Reissue Pat. No. 24,906 on the reverse side and over the adhesive a temporary removable low adhesion protective liner.

In applying the printed sections one removes the liner, wets the adhesive surface with a water-detergent solution to allow one to slide the section into registry and then remove the excess solution by squeegeeing the section. When such an adhesive-backed printed film is placed on the outside of, the sign, the usual order of printing on the film is followed, normally yellow, magenta, cyan and black, but if the film is to be placed on the interior of the front face of the sign, a mirror image is printed, and the order of printing the colored dots is reversed, so that when the adhesive-coated side of the film section is placed against the inside of the front face, the sequential order of the dots facing the viewer will be correct and the pictorial will be right-reading."

What is claimed is:

l. A method of producing a pictorial on transparent plastic films and application thereof to large internally illuminated signs to provide a pictorial having an inconspicuous splice, said method comprising the steps of separating into sections the pictorial to be reproduced, producing individual sections of said pictorial by appropriately four-color printing each section on a transparent film while leaving a different two-color printed border respectively on each of adjacent sections of the film, and overlap splicing and bonding adjacent borders in registry so as to bond said borders and supply only the amount of four-color printing at the overlapped areas necessary to provide the desired four-color density in all portions of the pictorial.

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